結果

問題 No.1181 Product Sum for All Subsets
ユーザー tokusakurai
提出日時 2020-08-21 22:30:44
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 45 ms / 2,000 ms
コード長 3,420 bytes
コンパイル時間 2,041 ms
コンパイル使用メモリ 193,560 KB
最終ジャッジ日時 2025-01-13 06:15:46
ジャッジサーバーID
（参考情報） 		judge1 / judge4
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 27
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i = 0; i < n; i++)
#define rep2(i, x, n) for(int i = x; i <= n; i++)
#define rep3(i, x, n) for(int i = x; i >= n; i--)
#define elif else if
#define sp(x) fixed << setprecision(x)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define sz(x) (int)x.size()
using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;
const ll MOD = 1e9+7;
//const ll MOD = 998244353;
const int inf = (1<<30)-1;
const ll INF = (1LL<<60)-1;
const ld EPS = 1e-10;
template<typename T> bool chmax(T &x, const T &y) {return (x < y)? (x = y, true) : false;};
template<typename T> bool chmin(T &x, const T &y) {return (x > y)? (x = y, true) : false;};
template<ll mod>
struct Mod_Int{
    ll x;
    Mod_Int() {}
    Mod_Int(ll y) : x (y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}
    Mod_Int &operator += (const Mod_Int &p){
        x = (x + p.x) % mod;
        return *this;
    }
    Mod_Int &operator -= (const Mod_Int &p){
        x = (x + mod - p.x) % mod;
        return *this;
    }
    Mod_Int &operator *= (const Mod_Int &p){
        x = (x * p.x) % mod;
        return *this;
    }
    Mod_Int &operator /= (const Mod_Int &p){
        *this *= p.inverse();
        return *this;
    }
    Mod_Int &operator ^= (ll k){
        Mod_Int ret = 1;
        while(k){
            if(k&1) ret *= *this;
            *this *= *this, k >>= 1;
        }
        swap(x, ret.x);
        return *this;
    }
    Mod_Int &operator ++ () {return *this += Mod_Int(1);}
    Mod_Int operator ++ (int){
        Mod_Int tmp = *this;
        ++*this;
        return tmp;
    }
    Mod_Int &operator -- () {return *this -= Mod_Int(1);}
    Mod_Int operator -- (int){
        Mod_Int tmp = *this;
        --*this;
        return tmp;
    }
    Mod_Int operator - () const {return Mod_Int(-x);}
    Mod_Int operator + (const Mod_Int &p) const {return Mod_Int(*this) += p;}
    Mod_Int operator - (const Mod_Int &p) const {return Mod_Int(*this) -= p;}
    Mod_Int operator * (const Mod_Int &p) const {return Mod_Int(*this) *= p;}
    Mod_Int operator / (const Mod_Int &p) const {return Mod_Int(*this) /= p;}
    Mod_Int operator ^ (ll k) const {return Mod_Int(*this) ^= k;}
    bool operator == (const Mod_Int &p) const {return x == p.x;}
    bool operator != (const Mod_Int &p) const {return x != p.x;}
    Mod_Int inverse() const {return *this ^ (mod-2);}
    friend ostream &operator << (ostream &os, const Mod_Int &p){
        return os << p.x;
    }
    friend istream &operator >> (istream &is, Mod_Int &p){
        ll a;
        is >> a;
        p = Mod_Int<mod>(a);
        return is;
    }
};
using mint = Mod_Int<MOD>;
const int MAX_N = 200000;
mint fac[MAX_N+1], ifac[MAX_N+1];
void init(){
    fac[0] = 1;
    rep2(i, 1, MAX_N){
        fac[i] = fac[i-1]*i;
    }
    ifac[MAX_N] = fac[MAX_N].inverse();
    rep3(i, MAX_N, 1){
        ifac[i-1] = ifac[i]*i;
    }
}
mint comb(int n, int k){
    return fac[n]*ifac[n-k]*ifac[k];
}
mint perm(int n, int k){
    return fac[n]*ifac[n-k];
}
int main(){
    init();
    int N; ll K;
    cin >> N >> K;
    mint x = K, tw = 2, y = x*(x+1)/tw;
    mint ans = 0;
    rep(i, N){
        mint a = y^i, b = x^(N-i), c = comb(N, i);
        ans += a*b*c;
    }
    cout << ans << endl;
}
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